It is certainly permissable, but I'm not sure why you would do that in a discussion forum. Are you aware of http://www.animalconcerns.org ? This site is hosted on EnviroLink and is, in fact, a directory of animal concerns (welfare and rights) organizations. Why not just suggest the content there (there's a form to do it) and then use it as a reference here when needed?

This is a discussion forum, not necessarily a phonebook for organizations (that's part of what EnviroLink.org and AnimalConcerns.org exist to do). Another reason is that inactive discussion threads get deleted after 90 days in the Animal Concerns area, so you are not creating a permanent record. This is another characteristic of a discussion thread vs. an archive site.